The numbers above are player market values, estimated by Transfermarkt. The factors considered in the calculation range from age and form to data analysis of recent performances. The real figure a club ends up paying for a player ultimately comes down to the market forces of supply and demand.

Lionel Messi and Junior Neymar top the list of most valuable footballers, and by a stretch. Cristiano Ronaldo, mostly due to his age (33), has slid down the list and now shares third spot with the young French winger Kylian Mbappe and England's prolific goal scorer Harry Kane. The peak age for a footballer is generally considered to be 25. The youngest two players on this list are Mbappe (19) and Alli (22).

It is interesting to note that all players among the top 20 are either forwards or midfielders. Five of them play for Barcelona FC and four are of French nationality.

Are there any surprises on this list? Anyone you think that should be included but isn't?